Spark-plug



narran STATES PATENT OFFICE.-

LEON CAMMEN, 0F NEW YORK, A ND AUGUST W. OFELDT, OF WEEHAWKEN, NEW JERSEY, ASSIGNORS TO NORTHWIND SPARK PLUG CORPORATION, 0F NEW YORK, N. Y., A CORPORATION OF DELAWARE.

SARK-PLUG.

Specification of Letters Patent.

.Patented June 22, 1920.

To all ywhom t ymay concern.'

Be it known that we, LEON CAMMEN, eitizen of the llnited States, and resident of borough of Manhattan, in the city, county, and State of New York, and AUGUST lV. OFELDT, citizen of the United States, and resident of lVeehawken, Hudson county, State of New Jersey, have invented certain new and usefulv Improvements in Spark- Plugs, of which the following` is a specification.

Numerous attempts have been made in the past years to produce a spark plug` with internal ,cooling of the center electrode rby a flow of air admitted from the outside on the suction stroke but practically all these attempts have failed for the following reasons.

In the first place.v the center electrode needs cooling especially when the engine is running at the heaviest load, as in tractor work when the tractor is pulling, or in car work on hills or when the car is running at high speed. But just then the vacuum in the cylinder'is low, and only little air can enter through the air valve in the spark plug. Had all this air been used for the cooling of the center electrode, it would do good, but in all constructions suggested hitherto, the air was admitted simply to the center chamber of the spark plug, and only a very small part of it came in direct contact with the center electrode. rl'herefore the amount. 'of cooling produced was insignificant.

ln the second place, ball check valves were used to controly the admission of air on the suction stroke, and its exclusion on the pressure and explosion parts of the cycle. E tensivc tests made by me have shown that the action of the ball is too slow for this ijmrpose, and that is a tendency on theI explosion stroke for the hot gases to blow past the ball. As a result of this the entire plug gets very hot.

These sources of trouble have been obviatcd in the construction set forth here.

In the drawings,

Figure 1 shows a section through the plug;

Fig. 2 shows a side View of the air inlet nut 3; and

Fig. 3 shows a top View of the same nut 3.

In thespark plug shown, 1 is the shell, 2 the insulator, shown here as porcelain, but which may also be of mica., lava, or any other suitable material, '4 is the tightening locknut the duty of which is vto hold the insulator in place. These parts are common to all spark plugs now on the market.

The shell 1 terminates in a plate electrode G,- a construction which is not new in itself. 'The center electrode 5 is in this case huilt as a tube having a central passage 7, said central passage opening at one of its ends into a chamber provided for this purposev in the air inlet nut 3, and its other end, as at S, into theV central chamber of the spark plug 9. At that end the center electrode ends in a solid piece 10 which may be either formed as an integral part of the tube, or attached to it in any of various ways, as bywelding, or screwing in.

The purpose ofv this ,construction is to provide ymeans for preventing the fouling of the plug by oil. As will be shown below, air enters intoV the passage 7 of tube during the suction stroke of the cylinder. AAt Spit passes into the center chamber 9 of the spark plug, and has to pass through the annular passage 11 in order to egress therefrom. lVhile doing so, it blows away any oil that might have settled in 11, and prevents its accumulation and carbonization.

The air inlet nut is provided with several holes or slots 12, by which, and the passage 13 in the top nut 14 it communicates with the external atmosphere. In its upper (in the position shownk in the drawing) part it is provided with aslight bulge 15 over which lies the disk valve 17 which is simply a thin round disk of hard metal, such as h ronf/.e or steel.

lWhen the engine is'not operating, or'during the suction stroke, air can enter freely through passage 13 in the top nut 14, and flow around the disk valve 17 into slots 12 and tube 5. On the compression and explosion strokes, however, the air pressure from inside forces the disk valve 17 against `the carefully machined or ground seat 16 in the top n'ut`14.

Numerous tests have shown that there is a very definite range` of movement for the valve 17 in a. spark plug during which it Will operate. 'lf the distance through which the valve 'is permitted to move is too small,

notenough nii. Wiil be emiiw suit, causing loss of powleiff and oveiiieu'in A of the valve. Tests have sit-own that *diei results are secureci 'when iiiedisi mii/e has a freedom 0 move-menig of the of 0.001 inch while very poor segu-e obtained with the valve having of motion of 0.005 in., exeep; on very 5 speed high compi'ession engines.

Variations may be Jesoited in Wiii Y, spirit and scope of my inven'sione :1a-m; remue parts thereof used wi'tiioue et'iiefe I claim: 1. In a spark plug" u. no' Lx-ode and e disk mii-e Je electrode, and te pii'even; air when the pressnfe in i?. electrode is greater Y 2. Ina spark ping"7 a, tuouifiicenter trede and e disk 'waive te enii; an' L,

eiectiode when the engine is not running, but to prevent said tadmission of air from outside of the engine when the pressure in the center tube electrode is greater than the atmospheric.

in a` spark plug', a tubular Center electede, and a disk valve admitting air to sai Center electrode When the engine is .not running, out preventing said admission of nir from. -the outsideo the engine when the pressure in the center tube electrode is gifeetei: than the atmospheriujpiessure, the mive being heid against its seat by said difference of pressure.

In e Spark piugge disk valve to reguizme the admission of air to the interior of Evhe ping chamber, said valve having :L freedom eti motion of the order 'of 000i inch.

r"gned ai; New York, in the county and Steh@ of New York, this 4 dey ofi August LEN CAMMEN, AUGUST W. OFELDT. 

